アブストラクト（36巻4号：神奈川歯学）

神奈川歯学

Japanese

Title　： 哺乳期ラット骨芽細胞にみられる脂肪滴の微細構造
Subtitle　：
Authors　： 小川洋一, 高橋常男
Authors（kana）　： おがわよういち, たかはしつねお
Organization　： 神奈川歯科大学口腔解剖学教室
Journal　： 神奈川歯学
Volume　： 36
Number　： 4
Page　： 228-252
Year/Month　： 2001 / 12
Article　： 原著
Publisher　： 神奈川歯科大学学会
Abstract　： 一般的に, 細胞内の脂肪は食餌中の脂質に由来するものと, 糖質などからde novo経路で合成されたものがある1). その脂肪は細胞学的には細胞内で脂肪滴として存在している. この脂肪滴は高エネルギー化学物質であるトリグリセリドの貯蔵系として重要な意義をもっている1, 2). 哺乳動物の脂肪組織は, 水, タンパク質を除くと, 重量の65～85%が脂質で, その約90%をトリグリセリドが占め, 少量の遊離脂肪酸, ジグリセリド, コレステロール, リン脂質, ごく微量のコレステロールエステル, そしてモノグリセリドなどが含まれる3～6). これらの結果は, 定性/定量的データを踏まえると, 細胞内脂肪滴は, 形態学的には単一構造物として観察されるが, “いわゆる脂肪滴”は細胞化学的にはいくつかの脂質類の混合成分から構成されている可能性や細胞機能に固有の脂質成分から構成される脂肪滴が同時に存在することが推察される. 脂肪滴は, 電子顕微鏡学的(電顕的)には, その表面張力から小さい脂肪滴は一般に球状形を呈しているが, 脂肪滴がより大きくなると, 不正円形から不規則な外形(時に著しく鋸歯状)になるなど, 種々の形態学的特徴を呈する.
Practice　： 歯科学
Keywords　： 脂肪滴, 分泌, 骨芽細胞, 哺乳期, 石灰化

English

Title　： Ultrastructure of Lipid Droplets in Osteoblasts Derived from Suckling Rats
Subtitle　：
Authors　： Yoichi OGAWA, Tsuneo TAKAHASHI
Authors（kana）　：
Organization　： Department of Oral Anatomy, Kanagawa Dental College
Journal　： Kanagawa Shigaku
Volume　： 36
Number　： 4
Page　： 228-252
Year/Month　： 2001 / 12
Article　： Original article
Publisher　： Kanagawa Odontological Society
Abstract　： This study was examined ultrastructurally the morphological characteristics of lipid droplets in the osteoblast, as well as the phenomenon of release to the extracellular space and calcium localization of the lipid droplets in parietal bone fragments from suckling rats. Lipid droplets as the structures accumulated by lipids were very often observed within the cytoplasm and the vesicles. These lipid droplets are approximately 0.3～1.0μm in diameter. Some of these were coalesced and became bigger (approximately 1.0～3.0μm in diameter), coming closer to the cell membrane on the osteoid side and released to the extracellular space. The smaller-sized lipid droplets have a tendency to be released in the intercellular space of osteoblasts. In bone tissue fragments of the weaned rats just after birth, size of osteoblasts, widths of the calcified bone and the osteoid seemed to be smaller, compared with the suckling rats, suggesting a close relationship between suckling and bone formation. Regarding the surroundings of the droplets (limiting membrane), a variety of cytoplasm interfaces of lipid droplets were observed：Some were clearly observed as a single or double limiting membrane, as a partial limiting membrane, or being lacking, and others between the two droplets were observed with the image of membranous structures invading from the outermost layer into the center. Lipid droplets electron-densely stained by lipid staining could be observed within the capillary lumen, surrounding and in both osteoblasts and osteocytes, in the osteoid, within the osteocyte lacunae. It is supposed that the appearance of lipid droplets widely spreading in mesenchymal cells supports the close relationship between lipid metabolism and bone formation. Also, the component source of lipid droplets within the osteoblast is surmised to be derived from chylomicron. Lanthanum crystal deposits were observed surrounding the lipid droplet, indicating the localization of Ca ions at the periphery of the droplets, also the existence of protein components with a Ca affinity in the outermost layer of lipid droplet. The same results were obtained in the potassium antimonite method. The existence of lipid droplets inside the calcified bone as well as the co-existence of calcifying spicules and lipid droplets indicate the possibility of cytophysiological role of fatty acid lipid droplets in the bone formation process. Based on the results above, this study strongly shows the possibility that ionized fatty acid molecules derived from the osteoblast may be contributed to provide Ca-enriched fields in proportion to the volume of ionized fatty acids, since they have an affinity with Ca ions.
Practice　： Dentistry
Keywords　：